A pharyngeal jaw evolutionary innovation facilitated extinction in Lake Victoria cichlids

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Science  27 Nov 2015:
Vol. 350, Issue 6264, pp. 1077-1079
DOI: 10.1126/science.aab0800

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The downside of innovation

Evolutionary innovation allows a species to invade a new niche or environment. Generally, the emergence of adaptive traits is thought to lead to diversification. Support for this process in nature, however, is mixed. McGee et al. show that the evolution of secondary jaws in fish may be an example of how innovation can reduce diversification (see the Perspective by Vermeij). Fish with secondary jaws are less able to rapidly ingest fish prey, which puts them at a competitive disadvantage to regularly jawed fish. Such competition could lead to reduced variation and the extinction of lineages with the trait.

Science, this issue p. 1077; see also p. 1038


Evolutionary innovations, traits that give species access to previously unoccupied niches, may promote speciation and adaptive radiation. Here, we show that such innovations can also result in competitive inferiority and extinction. We present evidence that the modified pharyngeal jaws of cichlid fishes and several marine fish lineages, a classic example of evolutionary innovation, are not universally beneficial. A large-scale analysis of dietary evolution across marine fish lineages reveals that the innovation compromises access to energy-rich predator niches. We show that this competitive inferiority shaped the adaptive radiation of cichlids in Lake Tanganyika and played a pivotal and previously unrecognized role in the mass extinction of cichlid fishes in Lake Victoria after Nile perch invasion.

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